Roof Curb For Fan Base Size 32 1/2 in to 44 1/2 in Curb Height 18 in Curb Inside Width 28 in to 43 in Curb Outside Width 31 in to 46 in Material Steel Standards NFPA 96 UL 705 UL 762 For Use With NFPA 96 UL 705 UL 762 Adjustability Adjustable Ventilation Type Ventilated Application Commercial Kitchen Curb Inside Length 28 in to 43 in Curb Shape Square Features Flashing Flange Finish Galvanized Flashing Flange Width 5 in